The epidemiological importance of bats in the transmission of rabies to dogs and cats in the State of São Paulo, Brazil, between 2005 and 2014

In Brazil, rabies control in dogs and cats was pioneered by the state of São Paulo with the adoption of the Pan American Health Organization recommendations for prophylaxis and control, which led to a reduction in rabies cases from 1994 onwards. As a result of these measures, the rabies virus (RABV) genetic lineage associated with dogs has not been found in the state since 1998, and all the cases in domestic animals reported since then have been caused by bat­associated lineages of RABV. In the light of this, this study sought to investigate rabies cases in dogs and cats in the state of São Paulo between 2005 and 2014 and identify the associated transmission cycles by characterizing the RABV lineages responsible for these cases. Nine samples from dogs (n = 5) and from cats (n = 4) were collected between 2005 and 2014. The tenth animal, a rabid cat, was analysed by a different laboratory. The N gene nucleotide sequences obtained were analysed with the neighbor­joining algorithm and Kimura 2­parameter model using the MEGA 6 program. Phylogenetic analysis revealed that the genetic lineages identified in all the samples were those circulating in Brazilian bats. The findings of this study demonstrate that bats play an important role in the transmission of rabies to domestic animals in São Paulo state and that emphasis should be placed on the implementation of public policies to support surveillance of chiropterans for rabies.(AU) i

Antigenic and genetic stability of rabies virus

Rabies virus (RABV) is a single stranded RNA genome virus that encodes five proteins: nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and RNA dependent polymerase (L). However, RABV seem to be remarkably stable antigenic and genomic differences among isolates from different species have been recognized for many years.Analysis of RABV isolates from different natural reservoirs reveals antigenic variants and/or genetic lineages with specific characteristics, suggesting selection and adaptation of viruses to each of the particular species. Such selections and adaptations are so specific that they allow for the identification of the natural reservoir of origin of a determined isolate.This work was conducted to investigate the genomic and antigenic stability of four different genetic lineages of RABV,originated from different host species, following successive passages in mice. Four RABV isolates (IP4005/10, IP964/06, IP3629/11 and IP4871/11) were inoculated intracerebrally into 3-4 weeks-old mice. After each passage, the viruses were examined in their antigenic profile with a panel of monoclonal antibodies to rabies virus antigens. Viral RNA wasextracted from the 1st, 5th and 10th passages and submitted to reverse transcription (RT) followed by polymerase chain reaction (RT-PCR), sequencing and phylogenetic analyses. Antigenic profile of the isolates did not reveal any recognizable alteration throughout. No nucleotide substitutions were noticed in the final sequences in any of genes sequenced fromthe four RABV isolates, with the exception of one nonsynonymous substitution in the putative protein P in position of amino-acid 222 in the isolate of non-hematophagous bat origin. These findings highlight the high antigenic and genetic stability of RABV, as opposed to the alleged high genomic variability of viruses with RNA genomes. On the other hand, itseems that different isolates may present different degrees of genetic stability, ...

Desmodus rotundus and Artibeus spp. bats might present distinct rabies virus lineages

In Brazil, bats have been assigned an increasing importance in public health as they are important rabies reservoirs. Phylogenetic studies have shown that rabies virus (RABV) strains from frugivorous bats Artibeus spp. are closely associated to those from the vampire bat Desmodus rotundus, but little is known about the molecular diversity of RABV in Artibeus spp. The N and G genes of RABV isolated from Artibeus spp. and cattle infected by D. rotundus were sequenced, and phylogenetic trees were constructed. The N gene nucleotides tree showed three clusters: one for D. rotundus and two for Artibeus spp. Regarding putative N amino acid-trees, two clusters were formed, one for D. rotundus and another for Artibeus spp. RABV G gene phylogeny supported the distinction between D. rotundus and Artibeus spp. strains. These results show the intricate host relationship of RABV's evolutionary history, and are invaluable for the determination of RABV infection sources.

Desmodus rotundus and Artibeus spp. bats might present distinct rabies virus lineages.

In Brazil, bats have been assigned an increasing importance in public health as they are important rabies reservoirs. Phylogenetic studies have shown that rabies virus (RABV) strains from frugivorous bats Artibeus spp. are closely associated to those from the vampire bat Desmodus rotundus, but little is known about the molecular diversity of RABV in Artibeus spp. The N and G genes of RABV isolated from Artibeus spp. and cattle infected by D. rotundus were sequenced, and phylogenetic trees were constructed. The N gene nucleotides tree showed three clusters: one for D. rotundus and two for Artibeus spp. Regarding putative N amino acid-trees, two clusters were formed, one for D. rotundus and another for Artibeus spp. RABV G gene phylogeny supported the distinction between D. rotundus and Artibeus spp. strains. These results show the intricate host relationship of RABV's evolutionary history, and are invaluable for the determination of RABV infection sources.